The present invention relates to the field of microelectromechanical devices, and more particularly, to microelectromechanical optical switches.
Microelectromechanical (MEMS) devices recently have been developed as alternatives for conventional electromechanical devices, such as relays, actuators, valves and sensors. MEMS devices are potentially low-cost devices, due to the use of simplified microelectronic fabrication techniques. New functionality also may be provided because MEMS devices can be physically much smaller than conventional electromechanical devices.
MEMS technology has been used to fabricate optical switches using MEMS reflectors, such as mirrors, to switch inputs thereto to selected switch outputs. Some MEMS reflectors in optical switches can be moved to provide the desired switch functions. For example, when a moveable MEMS reflector is moved to a reflecting position along a beam path, optical radiation that is conducted along the beam path can be reflected by the moveable MEMS reflector. When the moveable MEMS reflector is moved to a non-reflecting position outside the beam path, the moveable MEMS reflector may not reflect optical radiation from the beam path. Accordingly, moveable reflectors in optical switches can be positioned in respective reflecting or non-reflecting positions so that the optical switch can provide the desired switch functions.
A conventional moveable MEMS reflector can provide optical radiation from an input beam path to one of two output beam paths where the two output beam paths are orthogonal to one another. For example, in the reflecting position, a conventional MEMS reflector may be oriented along the input beam path at a 45 degree angle relative the input beam path so that optical radiation incident thereon is reflected in a direction that is orthogonal to the input beam path. In the non-reflecting position, the conventional moveable MEMS reflector may be positioned outside the input beam path so that optical radiation conducted along the input beam path is not reflected by the conventional moveable MEMS reflector but passes through rather than being reflected. Therefore, optical radiation conducted along the input beam path continues in a direction that is parallel to the input beam path. Consequently, conventional moveable MEMS reflectors can switch optical radiation in different directions.
Conventional moveable MEMS reflectors can be moved between associated reflecting and non-reflecting positions by respective actuators coupled thereto. Unfortunately, the actuators and associated latches (actuator/latch combinations) may occupy so much of a substrate that it may be difficult to form more than one actuator/latch and an associated reflector on a common substrate. Accordingly, some MEMS optical switches are created by forming a wafer with multiple dies, wherein one moveable reflector/actuator/latch combination is formed on each die as shown in FIG. 1. The wafer is diced to provide separate dies each having a reflector/actuator/latch combination formed thereon.
A MEMS optical switch can be created by coupling together separate dies having separate reflector/actuator/latch combinations formed thereon. However, the distance between reflectors in such MEMS optical switches may be relatively large so that optical radiation propagating through the optical switch may be degraded. Furthermore, assembling multiple dies can be difficult which can increase manufacturing costs. For example, optical radiation from an output of a first moveable reflector on a first die can be provided to an input of a second moveable reflector on a second die using an optical fiber to couple the output to the input. Coupling the optical fiber to the first and second moveable reflectors can increase the manufacturing cost. Accordingly, there is a continuing need to provide improved moveable reflectors and optical switches.
Embodiments of the present invention can provide a substrate and a moveable reflector, on the substrate, having first and second opposing surfaces, wherein the moveable reflector moves to first and second positions on the substrate. A latch is located on the substrate adjacent to the first surface of the moveable reflector opposite the second surface and coupled to the moveable reflector, wherein the latch holds the moveable reflector in the first and second positions. An actuator also is located on the substrate adjacent to the first surface of the moveable reflector opposite the second surface and is coupled to the latch, wherein the actuator moves the moveable reflector to the first and second positions.
According to embodiments of the invention, more than one moveable reflector/actuator/latch combination can be located on a common die. The moveable reflectors can be placed in close proximity to one another so that the optical beam path distance between the moveable reflectors can be reduced, thereby reducing attenuation of optical radiation along the optical beam path. Furthermore, optical radiation may propagate between moveable reflectors in free-space, thereby reducing the need for optical fibers to couple the optical radiation between reflectors on separate dies. In contrast, conventional first and second moveable reflectors/actuator/latches may be located on separate substrates so that optical radiation reflected by the first reflector propagates across the a first die to the second moveable reflector on a second die via an optical fiber.
In some embodiments, the first and second positions are first and second respective parallel reflecting positions. In other embodiments, the first position is a reflecting position and the second position is a non-reflecting position.
In other embodiments, the substrate is a die of a wafer and the optical switch includes a second moveable reflector that is located on the die adjacent to the second opposing surface of the first moveable reflector. The second moveable reflector has first and second opposing surfaces, wherein the second moveable reflector moves to first and second positions on the die. A second latch is located on the die adjacent to the first surface of the second moveable reflector opposite the second surface and coupled to the second moveable reflector, wherein the second latch holds the second moveable reflector in the first and second positions. A second actuator is located on the die adjacent to the first surface of the second moveable reflector opposite the second surface and is coupled to the second latch, wherein the second actuator moves the second moveable reflector to the first and second positions associated therewith.
In other embodiments of the present invention, moveable reflectors have a first reflecting position along an input beam path that reflects optical radiation from the input beam path along a first reflected beam path and a second reflecting position along the input beam path spaced-apart from the first reflecting position that reflects optical radiation from the input beam path along a second reflected beam path parallel to the first reflected beam path.
In some embodiments, a moveable reflector moves from the first reflecting position to the second reflecting position in a direction that is substantially orthogonal to a reflective surface of the moveable reflector. In other embodiments, the moveable reflector moves from the first reflecting position to the second reflecting position in a direction that is substantially parallel to the first and second reflected beam paths.
In other embodiments, a second moveable reflector has first and second associated reflecting positions along the first and second reflected beam paths, wherein the second moveable reflector reflects optical radiation from the first reflected beam path to a third reflected beam path and reflects optical radiation from the second reflected beam path to a fourth reflected beam path when the second moveable reflector is in the first reflecting position associated with the second moveable reflector. The second moveable reflector reflects optical radiation from the first reflected beam path to a fifth reflected beam path and reflects optical radiation from the second reflected beam path to a sixth reflected beam path when the second moveable reflector is in the second reflecting position associated with the second moveable reflector.
In other embodiments, the first and second moveable reflectors each move equal distances in substantially parallel directions between the respective first and second reflecting positions where the fourth and fifth reflected beam paths are co-incident. In other embodiments, the first and second moveable reflectors move unequal distances in parallel directions between the respective first and second reflecting positions where the fourth and fifth reflected beam paths are spaced-apart. In further embodiments, the first moveable reflector moves a distance in a first direction that is substantially parallel to a reflective surface of the first moveable reflector and the second moveable reflector moves the distance in a second direction that is substantially parallel to the first and second reflected beam paths where the fourth and fifth reflected beam paths are spaced-apart.
In other embodiments, an optical switch according to the present invention can include first and second moveable reflectors each having associated first and second reflecting positions, wherein optical radiation from a first one of a plurality of inputs is reflected from the first and second moveable reflectors to a first one of a plurality of outputs and optical radiation from a second one of the of the plurality of inputs is reflected from the first and second moveable reflectors to a second one of the plurality of outputs.
In related methods according to the present invention, a first moveable reflector can be moved to one of a first and second associated reflecting positions along an input beam path to reflect optical radiation from the input beam path to one of a first and second reflected beam paths. A second moveable reflector can be moved to one of a first and second associated reflecting positions along the first and second reflected beam paths to reflect optical radiation from one of the first and second reflected beam paths to an output.